英语翻译A manufacturer who produces breakfast cereals claims tha

英语翻译
A manufacturer who produces breakfast cereals claims that the amount of cereal in their packaging is always greater than what they have specified in the box.For a small size package,the manufacturer claims that they fill boxes to a mean weight of 368 grams with a standard deviation of 15 grams.Assume that the weights in the boxes are normally distributed.If a sample of 40 boxes is randomly selected:
a.What is the probability that the sample mean will be below 368g?
b.What is the probability that the sample mean will be above 365 grams?
c.What is the probability that the sample mean will be between 365 grams and 368 grams?
d.What is the probability that the sample mean will be between 365 grams and 370 grams?
e.Assume that we did not know the population mean.If the mean weight of cereals in a randomly collected sample of 40 boxes is 369 grams and the standard deviation is 10 grams,assuming that the amount of cereal in boxes are normally distributed,set up a 95% confidence interval for population mean.
f.If the packaging of this product specify the product net weight as “365g” (in its label),using your answer to part (g) above,comment on the manufacturer’s claim.
大意就是说面包店卖面包一个盒子368克的平均重量,偏差15.
第一题是求40个随机抽 平均值在368以下的概率
第二题是40个抽平均值在365克以上的概率
第三题 40个平均值在365-368的概率
下面2题不太懂

e.
SE(标准误差)=10/(根号下40)=1.58
查t-table表,95% confident 的情况下,t-value for （40-1）=39,也就是30的是3.030
magin of error=1.58*3.030=4.7874
so, 95% confidence interval for population mean is (369-4.7874, 369+4.7874) = (354.21,373.78)
f.
The manufacturer's claim is not correct, 365g is in the 95% confidence interval. The mean of the samples just should be around 365g which is not always larger than  what they have specified in the box.
e就是说让你求出一个mean的区间,包含的95%的sample的mean.也就是说,任意抽一组sample,你能95%确定它的mean落在这个区间里.
f是说让你评论一下制造商的话,制造商说mean是总是大于365g,这个数字在区间中间部分,所以他这个说法是不准确的.恩.
f里还提到了g?你没写我就不知道是什么了.
不保证对,我找不到书了.我也解释不好,好几章的内容呢,大致意思肯定没错,你再查查资料吧.
附,google搜的t-table表.